Strap buckle



1967 I E. c. RUTTY ETAL 3,336,639

STRAP BUCKLE Filed OCt. 27, 1964 /0\ 50 Z6 Z4 Z6 54 y in) 54 H6. 2 4 30 35 50 M 40 INVENTORS EDWARD C. RUTTY GEORGE E. DUDLEY BYZMy, WM7% ATTORNEYS United States Patent 3,336,639 STRAP BUCKLE Edward C. Rutty, Portland, and George E. Dudley, Wethersfield, Conn., assignors to The Stanley Works, New Britain, Conn., a corporation of Connecticut Filed Oct. 27, 1964, Ser. No. 406,796 3 Claims. (Cl. 24-74) The present invention relates generally to strap buckles and more particularly to a strap buckle having notable utility with nonmetallic strapping as, for example, for connecting the ends of a tensioned loop of nonmetallic strap encircling a package or the like.

It is a principal aim of the present invention to provide a new and useful buckle for nonmetallic strapping adapted for connecting a pair of strap ends without distorting and therefore without weakening the strap, and which thereby allows for using the full strength of the strap.

It is another aim of the present invention to provide a new and improved buckle for nonmetallic strapping which may be readily connected to a strap with or without access to a free end thereof and which provides for retaining the strap under tension without slippage.

It is another aim of the present invention to provide a buckle useful with nonmetallic strapping of the type formed with a plurality of elongated cords, of rayon for example, secured in side-by-side relationship with a suitable adhesive, and which is adapted for firmly holding a strap without severing or otherwise damaging the cords and with lateral distribution of the stress in the strap.

It is another aim of the present invention to provide a new and uesful strap buckle for nonmetallic strapping which facilities adjustment of the strap as for drawing a loop of strap about a package or the like.

A further aim of the present invention is to provide a new and improved plastic buckle of the type described having a molded single-piece construction with the desired strength, rigidity, and flexibility.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereafter set forth, and the scope of the application of which will be indicated in the appended claims.

In the drawings:

FIG. 1 is a perspective view on an enlarged scale of an embodiment of a strap buckle'of the present invention;

FIG. 2 is a reduced longitudinal section view of the strap buckle of FIG. 1;

FIG. 3 is an enlarged longitudinal section view, partly broken away, showing the strap buckle of FIG. 1 installed for connecting a pair of looped ends of nonmetallic strapping; and

FIG. 4 is a substantially full size plan view of another embodiment of the strap buckle of the present invention.

Referring now to the drawings in detail wherein like numbers represent like parts, the illustrated embodiment of the strap buckle of the present invention of FIGS. 1, 2 and 3 is a single-piece of hard and durable plastic construction molded in the elongated generally planar form shown in FIGS. 1 and 2 and adapted to take the form shown in FIG. 3 for connecting a pair of looped ends 12, 14 as of a loop of nonmetallic strap encircling a package, or other article and tensioned to secure the article. This embodiment 10 of FIGS. 1, 2, and 3 comprises three generally parallel elongated cross bars including a pair of side bars 16 and an intermediate bar 20. The cross bars are adapted to extend laterally of the strap and a pair of end bars 22, 24 connect the cross bars and provide therewith a sturdy and rigid frame 25 of generally rectangular shape. The cross bars 16, 20 are spaced to provide a pair of generally parallel slots or elongated openings 26 having sufiicient width to receive the looped ends '12, 14 of strapping and are formed with generally rounded cross sectional contours and therefore with pairs of opposed convexly curved edges or faces 30, 32 which define the slots 26. More specifically, the intermediate cross bar 18 is of generally cylindrical construction and of uniform cross section and therefore with simple convexly curved surfaces forming the faces 32. The cross bars 16 in contrast have a gradually diminishing cross section from substantially the lateral centerline of the frame to provide compound convexly curved surfaces forming the faces 30.

A pair of locking bars 40 having a length substantially equal to but less than the length of the slot openings 26 are integrally molded with the frame 25 and are connected with the frame by longitudinally extending arms or webs 44 having a limited thickness. The webs 44 are of generally L-shape and comprise relatively long leg portions 47 connected to the cross bars 16 adjacent the corners of the frame 25 and relatively short leg portions 48 connected to ends of the locking bars 40. The webs 44 are longitudinally flexible for locating the locking arms 40 in overlying relationship with the slots 26, and accordingly, the looped ends 12, 14 of strap may be conveniently inserted through the slots 26 and onto the locking bars 40 with the looking bars thereafter serving to prevent withdrawal of the loops through the slots 26, for which purpose the locking bars are dimensioned to have a width greater than that of the slots. This installation of the buckle onto the looped ends of strap may also be conveniently accomplished by inserting a free end 49 of strap through the slot 26, inwardly of, over and around the respective locking bar, and back through the slot.

The locking bars 40 are formed with a generally triangular or tear-drop cross section and are molded as seen in FIG. 2 with the tear-drop inverted relative to its locking position shown in FIG. 3 so that by reversely bending the webs 44 the locking bars can be located symmetrically above the slot openings 26 and with the apexes 50 of the tear-drops inserted into the slots between the opposed faces 30, 32. The locking bars 40 have a substantially constant cross section and oppositely facing angularly related generally planar locking faces 52, 54 formed to cooperate with the convex faces 30, 32, respectively, for gripping and thereby restraining the strap on the buckle. Accordingly, when the lower or outer overlapping portion 60 of the loop of strap is placed under tension, the loops 12, 14 of strap are wedged between the planar faces 52, 54 of the locking arms and the convexly curved or arcuate faces 30, 32 of the buckle frame, and the buckle functions as a self-locking buckle providing a wedging or restraining force which increases with the tension on the strap.

Due to the orientation and contour of the cross bars 16, 20 and the locking bars 40, the reactive force balancing the active force or tension on the strap results from: 1) the frictional engagement of the outer loop portion 60 with the inner loop portion 62, (2) the wedging action by the opposed faces 54 and '32, (3) the frictional engagement of the loop with the locking bar, (4) the wedging action by the opposed faces 52 and 30, and (5) the frictional engagement of the inner loop portion 62 with the convexly curved face 30 of the cross bars 16 and with the other loop portion 60. This distribution of the reactive force along the strap enables the strap to be held or secured by the buckle without unduly distorting and therefore without damaging a nonmetallic strap, which in the conventional form is constructed with a plurality of cords, of rayon for example, secured by an adhesive in side-by-side relationship and which has sub- O stantial strength in tension but which is relatively weak in shear. The resulting distribution of the reactive force has thereby enabled the buckle to firmly hold or grip strapping of this material without exceeding the shear limit of the strap.

It can also be seen that the opposed faces 54, 32 provide for wedging and thereby restraining the strap in a uniform manner across the strap and that the frictional engagement by the strap with the locking bar 40 is substantially uniform across the strap. Moreover, it can be seen that inasmuch as the gripping face 30 is a compound convexly curved surface and the overlapping portions 60, 62 of the loop pass over this face, the stress on the lateral edges of the strap is partially alleviated to prevent overstressing and as a result prevent damaging the strap at its lateral edges which, being nearly fully exposed, are the most vulnerable to superficial damage and should therefore be held to within a lower stress limit. Additionally, the planar edges 52, 54 of the locking bars have an angular relationship for locating the locking bars 40 substantially symmetrically within the slots 26 and with the planar edges 54 extending tangentially of the inner overlying portions 62 of the loop so that the outer or tensioned overlying portion 60 of the loop functions to retain the locking bars in this symmetrical relationship. Additionally, it is preferred that the angle between the planar faces 52, 54 is sufiicient to prevent the locking bars 40 from being jammed Within the slots 26 as a result of the tension on the strap and therefore to allow the locking bars to be withdrawn from the slots when the tension is relieved to adjust the strap or remove the buckle.

A modified embodiment of the strap buckle of the present invention is shown in FIG. 4 with a pair of L-shaped webs 44 for each of the locking bars 40 and with the L-shaped webs connected between the frame and the ends of the locking bars in the manner of the embodiment of FIGS. 1, 2 and 3. This embodiment thereby provides for more securely mounting the locking bars 44 and would of course require the free ends of the strap to be fed through the slots and around the locking bars.

Thus it can be seen that the strap buckle of the present invention is particularly useful with nonmetallic strapping of the type having a plurality of elongated cords and thereby having substantial strength in tension and comparatively less strength in shear. Moreover, the strap buckle is adapted to tightly and evenly grip the strapping therefore without unduly distorting or concentrating stress within the strapping. Further, the strap buckle of the present invention provides for alleviating the stress at the lateral edges of the strapping and thereby avoid rupture of the strapping where it is superficially damaged at its lateral edges. Additionally the strap buckle of the present invention has an economical single-piece construction which is easy to install and remove.

As will be apparent to persons skilled in the art, various modifications and adaptations of the structure above described will become readily apparent without departure from the spirit and scope of the invention, the scope of which is defined in the appended claims.

We claim:

1. A single-piece molded plastic buckle for connecting a pair of looped ends of nonmetallic strapping comprising a rigid frame with generally parallel cross bars including side and intermediate bars having pairs of opposed faces with compound and simple convexly curved surfaces respectively and defining a pair of slots dimensioned for receiving looped ends of nonmetallic strapping, a pair of locking bars of less length than the slots adapted for receipt within the looped ends of strapping, said locking bars having opposed angularly related generally flat faces cooperative with the convexly curved faces to wedge the strapping therebetween, and L-shaped flexible web means connecting the locking bars and the frame having relatively long leg portions extending from the frame adjacent the corners thereof and short leg portions extending from the ends of the locking bars.

2. A single-piece integrally molded plastic buckle for connecting a pair of looped ends of nonmetallic strapping comprising a rigid frame with three laterally extending generally parallel cross bars having opposed convexly curved faces defining a pair of slots for receiving looped ends of strapping, a pair of elongated locking bars having widths greater than the widths of the slots respectively, said locking bars having generally tear-drop cross sectional contours and angularly related generally planar faces cooperative with the convexly curved faces for wedging the strapping therebetween, and arm means for connecting the locking bars to the frame longitudinally flexible for positioning the locking bars in generally symmetrical relationship within the slots and with said generally planar faces in contiguous relationship with said convexly curved faces.

3. A strapping buckle for connecting a pair of looped ends of elongated nonmetallic strapping comprising a rigid longitudinally extending frame with generally parallel laterally extending cross bars including side and intermediate bars having pairs of opposed faces defining a pair of slots dimensioned for receiving the looped ends of nonmetallic strapping, said pairs of opposed faces having compound and simple convexly curved surfaces respectively, a pair of laterally extending locking bars adapted for receipt within the looped ends of strapping having widths greater than the widths of the slots respectively, said locking bars having opposed faces cooperative with the opposed faces of the cross bars respectively to wedge the strapping therebetween, and means connecting the locking bars to the frame adapted for adjustably and independently longitudinally positioning the locking bars between the opposed faces of the slots to permit each of the locking bars to assume a position for wedging the nonmetallic strapping against both of the opposed faces defining the respective slot.

References Cited UNITED STATES PATENTS 1,054,861 3/1913 Moses 24-259 3,206,816 9/1965 Vilcins et a1 24-74 FOREIGN PATENTS 83,172 10/1895 Germany. 721,664 6/ 1942 Germany.

WILLIAM FELDMAN, Primary Examiner.

E. SIMONSEN, Assistant Examiner. 

3. A STRAPPING BUCKLE FOR CONNECTING A PAIR OF LOOPED ENDS OF ELONGATED NONMETALLIC STRAPPING COMPRISING A RIGID LONGITUDINALLY EXTENDING FRAME WITH GENERALLY PARALLEL LATERALLY EXTENDING CROSS BARS INCLUDING SIDE AND INTERMEDIATE BARS HAVING PAIRS OF OPPOSED FACES DEFINING A PAIR OF SLOTS DIMENSIONED FOR RECEIVING THE LOOPED ENDS OF NONMETALLIC STRAPPING, SAID PAIRS OF OPPOSED FACES HAVING COMPOUND AND SIMPLE CONVEXLY CURVED SURFACES RESPECTIVELY, A PAIR OF LATERALLY EXTENDING LOCKING BARS ADAPTED FOR RECEIPT WITHIN THE LOOPED ENDS OF STRAPPING HAVING WIDTHS GREATER THAN THE WIDTHS OF THE SLOTS RESPEC- 